The Production of these iron balls dates back to the Ming Dynasty (1368-1644). The inside is hollow and each ball has a sounding plate inside. One emits a high tone, the other a low tone. According to the Chinese traditional medical theory of Jingluo, the hand contains a network of channels which circulate vital energy. Acupuncture points are distributed along these channels. Rotating the iron balls within our hand stimulates the acupuncture points- leading to better circulation (and unlocking vital energy). The Health Balls are placed in the palm and then rotated in a circular manner. In China, it is common to see a person using the Health Balls while taking a walk.